{"id":5530,"date":"2021-10-05T16:30:19","date_gmt":"2021-10-05T22:30:19","guid":{"rendered":"http:\/\/www.realtimerendering.com\/blog\/?p=5530"},"modified":"2021-10-05T16:34:07","modified_gmt":"2021-10-05T22:34:07","slug":"back-of-the-business-card-ray-tracers","status":"publish","type":"post","link":"https:\/\/www.realtimerendering.com\/blog\/back-of-the-business-card-ray-tracers\/","title":{"rendered":"Back of the Business Card Ray Tracers"},"content":{"rendered":"\n

Basic ray tracing is a simple algorithm. As sometimes given as proof, there are two business card ray tracers I know of: Paul Heckbert’s and Andrew Kensler’s. You can see Andrew’s explanation here<\/a> (as well as links to ports), the leet<\/a> code here<\/a>, and an involved revisit and optimization and CUDA-ization of this code by Fabien Sanglard here<\/a>.<\/p>\n\n\n\n

Andrew’s dates from somewhere during 2005-2009<\/a>, when he was avoiding writing his thesis. Paul’s dates from 1987, including tricks he learned from Darwyn Peachey and Joe Cychosz. His links are here<\/a>, the code’s here<\/a> and unminimized here<\/a>, and the whole thing is written up in Graphics Gems IV<\/em>. Which I wish was free on the (legal) web at this point… But through the miracle of Google Books, you can find most of the article here<\/a> and missing page 379 (just the code listing) here<\/a>.<\/p>\n\n\n\n

Yesterday I realized I likely had never seen the output of Paul’s ray tracer. I installed Ghostscript to look at his file, but it was pretty beat:
<\/p>\n\n\n\n

\"\"\/
Yeah, definitely ray tracing, or something<\/figcaption><\/figure>\n\n\n\n

So I compiled Paul’s minimized code, finding a few small syntax errors that VS 2019 didn’t like so much. Adding a PPM header to the image file dumped, it’s this:
<\/p>\n\n\n\n

\"\"<\/a>
32 x 32<\/figcaption><\/figure>\n\n\n\n

So, better, I can see spheres. I upped the resolution – it took a whole 10 seconds to run on a single CPU:<\/p>\n\n\n\n

\"\"<\/a>
1024 x 1024<\/figcaption><\/figure>\n\n\n\n

Not stunning, but now I know!

And today I ran across a set of lecture slides<\/a> from the University of Utah which shows both of these business-card ray tracers’ results, page 22 on. Oddly, the image shown there has different colors – maybe gamma correction or something?<\/p>\n\n\n\n

Anyway, now you can say you’ve seen it, too. And here’s the back of my copy of Paul’s business card, in the flesh, as it were:<\/p>\n\n\n\n

\"\"<\/a><\/figure>\n\n\n\n

Me, I was thrilled that 34-year-old code basically still ran, with minimal messing about.<\/p>\n","protected":false},"excerpt":{"rendered":"

Basic ray tracing is a simple algorithm. As sometimes given as proof, there are two business card ray tracers I know of: Paul Heckbert’s and Andrew Kensler’s. You can see Andrew’s explanation here (as well as links to ports), the leet code here, and an involved revisit and optimization and CUDA-ization of this code by […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[642,55],"class_list":["post-5530","post","type-post","status-publish","format-standard","hentry","category-misc","tag-business-card","tag-ray-tracing"],"_links":{"self":[{"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/posts\/5530","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/comments?post=5530"}],"version-history":[{"count":3,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/posts\/5530\/revisions"}],"predecessor-version":[{"id":5536,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/posts\/5530\/revisions\/5536"}],"wp:attachment":[{"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/media?parent=5530"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/categories?post=5530"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.realtimerendering.com\/blog\/wp-json\/wp\/v2\/tags?post=5530"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}